#!/usr/bin/env python
#
# Copyright 2007 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
















"""Base operation class."""


__all__ = ['Operation']


class Operation(object):
  """Base class for all mapper operations.

  All operations should implement __call__(self, ctx) function, which will be
  called upon operation yield.
  """

  def __call__(self, ctx):
    raise NotImplementedError("__call__() not implemented in %s" %
                              self.__class__)
